A number of injector-actuated syringes and powered injectors for use in medical procedures such as angiography, computed tomography and NMR/MRI have been developed. For example, U.S. Pat. No. 4,006,736 discloses an apparatus for injecting fluid into the vascular system of a human being or an animal. Likewise, U.S. Pat. No. 4,677,980 discloses an angiographic injector and syringe wherein the drive member of the injector can be connected to, or disconnected from, the syringe plunger at any point along the travel path of the plunger via a releasable mechanism requiring rotation of the syringe plunger relative to the piston. Each of the injectors disclosed in U.S. Pat. Nos. 4,006,736 and 4,677,980 includes a pressure jacket that is breach or rear loaded with a syringe.
U.S. Pat. No. 5,300,031 discloses an injector system in which a syringe is loadable in and unloadable from a pressure jacket of an injector through an open front end in the pressure jacket. The injector system of U.S. Pat. No. 5,300,031 permits replacement of a syringe without retraction of the syringe plunger drive or disconnection of injection tubing connected to the syringe.
A front-loading syringe and injector system is disclosed in U.S. Pat. No. 5,383,858. The syringes disclosed in U.S. Pat. No. 5,383,858 can be readily and securely front-loaded directly and accurately on the injector or on a pressure jacket attached to the injector, thereby facilitating the loading-unloading operation as compared to prior systems. In the front-loading system of U.S. Pat. No. 5,383,858 and other currently available front loading systems, a user manually aligns the syringe in a desired orientation relative to the injector and manually inserts and locks the syringe in place.
In the system of U.S. Pat. No. 5,383,858, for example, an interlocking, releasable mechanism is activated and released upon proper axial and radial alignment and subsequent manual rotation of a rearward portion of a syringe relative to a front wall of the injector housing. In one embodiment, the releasable mechanism includes slots on the front wall of the housing for receiving retaining flanges on the rearward end of the syringe. The syringe is manually rotatable to engage the retaining flanges with associated or cooperating flanges on the injector mounting mechanism. The releasable mechanism also includes an annular sealing member on the injector housing front wall against which a resilient annular sealing member or flange on the syringe becomes seated as the syringe is positioned on the mounting mechanism. The resilient annular sealing member and the retaining flanges on the syringe receive the flanges on the injector mounting mechanism therebetween with an interference fit.
The syringe plunger of U.S. Pat. No. 5,383,858 must be appropriately axially and radially positioned relative to the drive member during loading of the syringe upon that injector system so that rotation of the syringe during loading will also cause engagement of the drive member and the syringe plunger.
Although front-loading syringes represent a significant advancement in the area of injector-actuated syringes and powered injectors for use therewith, the loading and unloading procedures therewith require significant operator time/involvement to ensure secure engagement. For example, the operator must ensure that the syringes of current front-loading systems are first properly aligned with and then securely connected to the injector and that the plunger is engaged by the injector drive member. These steps can require substantial time, dexterity and strength as a result of, for example, alignment requirements, awkward and complex motions and close design tolerances. In many cases the injector may also be positioned so that it is difficult for the operator to access the injector to load a syringe thereon. Moreover, injector heads are typically not securely anchored and can move during syringe loading, further complicating loading of a syringe thereon.
It is very desirable to develop new syringes, injectors, injector systems and methods to reduce operator time/involvement in loading the syringe onto the injector and/or in connecting the syringe plunger to the injector drive member, while ensuring secure engagement between the syringe (including the syringe plunger) and the injector.